1. Field of the Invention
The present invention relates to a global positioning system (xe2x80x9cGPSxe2x80x9d) unit operable to generate a track log of a track traversed by a user and to display a track display representative of the track. More particularly, the invention relates to a GPS unit operable to display a track display including at least one track characteristic indicative of a feature sensed by the GPS unit or one or more sensors coupled with the GPS unit.
2. Description of the Prior Art
The global positioning system (xe2x80x9cGPSxe2x80x9d) is an electronic surveillance navigation system which permits users to determine their position with respect to the Earth. Global positioning may be determined with a handheld GPS receiver which detects and decodes signals from a number of satellites or biting the Earth. The signals from each of these satellites indicate the position of the satellite and the time at which the signals were sent. To decode the satellite signals, known as spread spectrum signals, and thereby calculate desired position and navigational data, a GPS receiver must first xe2x80x9cfindxe2x80x9d or acquire the signals emitted from a minimum number of satellites. Once the receiver is xe2x80x9clocked onxe2x80x9d to the spread spectrum signals, the user""s global position and other navigational data (e.g., velocity of movement) can be calculated.
In addition to determining the user""s location information, many GPS units are operable to display the user""s recent and present location as a track display. As the user traverses a track, the GPS unit generates a track log. The GPS unit then displays the track display, or electronic xe2x80x9cbreadcrumbxe2x80x9d trail, representative of the track. One such GPS unit is sold by Garmin Intemational, Inc., under the trade name e Trex Summit.
Prior art GPS units, however, are not operable to display a track display having characteristics indicative of a feature, such as elevation or altitude, water depth, or a heart rate of the user at a particular location, sensed by the GPS unit or additional sensors coupled with the GPS unit. Without illustrating additional information, the track display provides nothing more than an indication of where the user has traveled.
Accordingly, the need exists for an improved track display which displays additional information regarding features sensed by the sensor in relation to a location as determined by the GPS-based tracking or navigation device for the track traversed.
The present invention solves the above-described problems and improves upon the prior art of GPS units. In particular, the invention provides a GPS unit operable to display a track which illustrates not only the GPS unit""s location, but also features such as altitude, water depth, heart rate of a user, or other characteristics, such as rate of ascent or descent, speed, acceleration, etc.
A first embodiment of the present invention includes a GPS unit coupled with an altimeter. The GPS unit calculates its current location and stores data representative of previous locations in a conventional manner. The altimeter determines an altitude or elevation of the GPS unit and sends a corresponding signal to the GPS unit. The GPS unit is operable to display a track display having characteristics that indicate a change in elevation as sensed by the altimeter. Specifically, if the altimeter senses that a track the user has traversed increases in altitude, the GPS unit displays a track display that visually indicates the increasing altitude. In one embodiment, this is done by displaying a track display of increasing width as the altitude increases. Conversely, if the track decreases in altitude, the track display decreases in width. Alternatively, the track display may include a symbol for a change in elevation. For example, for every 100 feet increase in elevation, the track display may display an up arrow, and for every 100 feet decrease in elevation, the track display may display a down arrow. Another alternative may use color to indicate the change in elevation. For example, an increase of 100 feet per a ten minute interval may be denoted by a red track display segment, and a decrease of 100 feet per a ten minute interval may be denoted by a green track display segment. If the user does not change elevation more or less than 100 feet per a ten minute interval,the track display segment may remain black.
A second embodiment of the present invention is a GPS unit coupled with a sonar transducer. The sonar transducer determines a depth of a body of water in a conventional manner and then sends a corresponding signal to the GPS unit. The GPS unit is operable to display a track display, including an indication of a change in depth, using any of the above track display characteristics. Similar to the change in elevation, the track display""s width may increase as the depth increases and decrease as the depth decreases.
A third embodiment of the present invention is a GPS unit coupled with a heart rate monitor. A processor of the GPS unit may also include a computer program for calculating calorie expenditure based upon exertion. In the third embodiment, a track display may display a green track if the pulse rate is within a safe and acceptable range. Conversely, the track display may display a red track if the pulse rate is outside the safe and acceptable range. Alternatively, the track display may display a pulse rate value overlaid on the track""s width, wherein the pulse rate varies with a rate of ascent or descent.
The GPS unit of the present invention may also be equipped to store in the GPS unit""s memory a track traversed, map data corresponding to a track to be traversed, or routing algorithms based upon input starting and destination points operable to determine a particular track. Accordingly, when traversing the stored track (or track retrieved from the stored map or routing algorithm), a user of the GPS unit has an indication of an upcoming feature, depending on whether the sensor is an altimeter, sonar transducer, etc.
In addition to the above sensors of altimeter, sonar transducer, and heart rate monitor, the GPS unit of the present invention may also be coupled with other sensors or a combination of sensors for sensing other features. As with the above-described embodiments, the GPS unit is operable to display a track display with characteristics indicative of a change in the feature sensed by the sensor. For example, the GPS unit may be coupled with a thermometer for sensing a temperature of an environment in which the GPS unit is located. As the temperature increases, a corresponding portion of the track display may be colored red. Conversely, as the temperature decreases, the corresponding portion of the track display may be colored blue. Other sensors may include an oxygen content sensor and/or a light intensity sensor.
These and other important aspects of the present invention are described more fully in the detailed description below.